The analysis shows that these remedies and some antispasmodic drugs that are no longer widely prescribed work well, researcher Alexander C. Ford, MD, tells WebMD.

Newer drugs that once held great promise for the treatment of the poorly understood bowel disorder have largely proven disappointing, either because serious side effects emerged or they were not very effective.

"Most of the treatments we examined have fallen out of clinical favor," he says. "But they work, they are cheap, and they're far less toxic than some of the newer drugs."

Some IBS Drugs Pulled From the Market

Surveys suggest that anywhere from 5% to 20% of people suffer from irritable bowel syndrome, a disorder with a wide range of symptoms that may include crampy abdominal pain, gas, diarrhea, and/or constipation.

In February 2000, Lotronex became the first drug approved in the U.S. specifically to treat IBS, but it was withdrawn from the market later that year because of potentially life-threatening gastrointestinal side effects.

The drug was later reintroduced, but its use is now restricted to women with severe diarrhea-predominant IBS who have failed other treatments.

In March 2007, another IBS drug, Zelnorm, was also withdrawn from the market by its maker, Novartis, at the request of the FDA because of an increased risk for heart attack and stroke.

"These new-generation drugs were going to be the magic bullets for IBS, but it didn't turn out that way," King's College London professor of general practice Roger Jones, DM, FRCP, tells WebMD. "I think this new paper is important because it shows patients and their physicians that these older treatments can be effective."

Peppermint Oil and Fiber

Ford and colleagues combined the results from 12 studies comparing fiber with placebo or no treatment, 22 studies comparing different antispasmodic drugs to placebo, and four studies examining treatment with peppermint oil.

Although there were fewer peppermint oil studies, the trials were well designed and all showed peppermint oil to be effective.

Other highlights of the analysis include:

Based on the combined data, the researchers estimated that one in 2.5 patients would get significant relief of symptoms if treated with peppermint oil, compared to one in five patients taking antispasmodics and one in 11 patients taking fiber. Peppermint oil is sold in capsules, and the study participants took about 200 milligrams two or three times a day.

Insoluble bran-based fibers were not very effective, but soluble psyllium-based fiber treatments like Metamucil were. When phyllium therapies were considered on their own, one in six treated patients had significant improvement in symptoms.

When the 22 antispasmodic studies were combined, the drug scopolamine was among the most effective. The researchers recommend scopolamine, which is extracted from the corkwood tree, as the first-line antispasmodic treatment for IBS.

Ford and colleagues concluded that psyllium-fiber therapy is a good first-line treatment for constipation-predominant IBS, while peppermint oil and scopolamine are good choices for diarrhea-predominant IBS.

The analysis appears in the latest issue of BMJ Online First. In an accompanying editorial, Jones writes that the findings should reawaken interest in these treatments and spur research into their use for IBS.

"We really don't know which patients benefit most from which type of treatment," he tells WebMD.